Iron oxide-alkali metal ferrate catalyst and its method of preparation



Patented Dec. 7,

tof Delaware This invention is directed :toa method ior pparingawcomposition: adaptedto be used as: a catalyst. Moreparticularly, this invention relates to a method for preparing aspromoted catalystwfor utilization :inthe hydrogenation oil carbonoxides.

periodic-table such as the oxides of iron, cdbfilt and nickel, 13 :Italso known to use such oxides as catalysts either alone or supported onan inert:

m eri uc est a um tie el h (941G oth 9 2 umming ag n s-y 1 I e al b n kawe to add to the active catalytic materialim thecat aly st composition asuhstance usually designated asa promoterwhich exerts a.speciflceflecton the.

catalyst? t'vity, selectivity of the reactantsfltd high conyersiqn ofthereactantsto desired prod ucts bverfm uch long-erjberiods of operation"than is possible when using an un lmoted catalyst;

It is theybbject of theinvention cabinet/meta method for preparinganimbioiked catalyst. fAnother object of the present invention is to;devise a method for preparing e catalylst particuIa 'ly adapted forinfthe"Fischer Tropschsynthesis) A further object of this invention isto prepare a catalyst that maybe utilized in the synthesis; of high yiels of useful fpifoducts by the hydroge erationp l l The present inventionmay be described briefly asinvolving the'preparation of a catalyst com-"prising a; major portion of iron or an iron oxide as l the activecatalyticmaterial and a min-or pori tionwofanalkali metalferrate suchaspotassium ferrate (KzFeOQ 11 as the promoting material: 1 The methodof tpreparationwcomprises the 1 steps of forming an alkali-metal ferrateby adding t to a ixt e 01F H2 a nal w telh 2xide an oxidlging agent suchas trominaedding the thu formed alkali metal ferrate to thet iron or n;ox qeb x t WWMQIM QWM twee ama @QQ P 1 351 LWFWWeWS $943.9 1 31%.;

A PATENT I IHRONOXIDELALKALNI marnnrnnann on'r; H ALYST AND 1717sMETHOD: on mamas-n Max A. Mosesmain Baytowiii"rex; assi ndi, by mesneassignments, to Standard Oil Develop-- ment Company Elizabeth N J acorporation ixttre ata e evated temperatureof about 1000 Ii:inthflbrsence of air to obtain the finished catal t; Following theheattreatment in the fiof aitQ the catalyst is then reduced at a 1temperature inutherangebetween 700 and 1600 ifTh alkali metal f-erratepromoter, for example, pet ssium ferrata-to beaddedtothe catalyst may brepa red in a-number of ways. In the preanimonium hydtogide to cause theprecipitation LEeKQH); andthe ferrichydroxide thus form-ed is filtei edandthensl-urried with water. The ate rslurijywis admixed with solid KOHand to the mi are is addedslowly liquid bromine and solid Kenun i the mitureis saturated with res ect tothe latten The reaction mixture shouldbekept at a: tempe aturebeloiyabout 140 F. The mixture 'nay then be heatedcarefully with stirring for about one-half hounat about 140 F., allowed-to ;coo1, and the top; layer removed from the reaction ""Ifhetopj layeris dried in a vacuu and then washed with alcohol until substantiaiiy ieof alkali; The alcohol-washed material is also dried steam to produce apotassium ferrate substantially free from contaminating substances t Jtassiiim errate is then added to a owdered n a er to powdered oxide ofiron such erric oxide oralpha and gamma ferric siuniferrate he add-ed tothe active catalytic material such that; the finished catalyst willcomprise ahQut QtZ tO ZO weight per cent potassium 1 feifiiatehasd,onithe iron or iron' oxide employed.

Th mixture of potassium ferrate and iron or iron oxidefis milled,preferably in the presence of a smnre eiimb; alcohol, dried at atemperaabttt'a'am iendo ed. The piiled mahentheated at sfuperatmospherictem- *potassiumgbromate in small amounts in the finish dtcatalyst ispot; objectionable since both of thesesubstances may have a tendency topromote l the etiviae iifonoxidecatalyst in the hym ar ens nihas seactiq The practice of thepresent invention will he daily desired thatsuflicient p0ta.s

flhe ptesenceloi oth potassium bromide and iiaiiqfi iees ui ie was lyQ je i stirring. Suflicient solid KOH is added to the re: action mixture sothat the latter is completely saturated with respect to the alkali. Atthis'point,

it is preferable to add an excess oi solid 'KOH'to. the mixture, forexample, parts by weight of excess alkali, before heating the mixturewith,

stirring at a temperature oi- 1,410 F: for approximately one-half hour.

The heated mixture is allowed to cool and the 7 top layer comprisingpotassium ferrate is decanted from the total mixture and dried'underi' vpartial vacuum. Alkaline material remaining in the dried potassiumferrate may be removed bysuccessive washings and decantations withalcohol. The potassium ferra-te is then redried under vacuum and, asproduced in thismanner, is,

substantially free from alkalinecontaminants. and.

contains minor portions of potassium bromideor potassium bromate asillustrated by the following analysis:

v Percent IQFeOr 75.0 KBr 20.0 KBIO3 5.0

by weight ofpotassium ferrate per IOO-partsby weight of ferro-ferricoxide in the hydrogenation of carbon monoxide is exemplified ing data:

The catalyst prepared in accordance with theabove procedure is placed ina reaction chamber and reduced in the presence of; hydrogen for-24-hours at a temperature of'700 F; and atmospheric" pressure. The hydrogenis passed over the cata-' lystat a rate of 1000 volumes of hydrogen pervol-" ume of catalyst per hour; Asynthesis gas mixture comprising onepart of hydrogen per part; of carbon monoxide is then passed over thecata-' lyst at a pressure of 150 pounds per square inch gauge, atemperature of 575 F., and a rate'of 200 volumes per volume of catalystper hour.

This catalyst was employed in the synthesis-of hydrocarbons from carbonmonoxide'and hydro Samples ofthe products were examined during each24-hour"period.- During gen for 1736 hours.

the first 508 hours the CO conversioninmole per cent declined from aninitial figure of-97'.9

to 91% while the selectivity ratio of C4 and heav ier hydrocarbonsproduced to total product-111* mole per cent increased-froman initialfigureof 64% to as much as 78% andafter '508 hours; operation was 73.1During this period of time, the yield of 04+ hydrocarbons in cc. percubic meter of hydrogen and carbon monoxide consumed varied within awide range from 135' at the outset to as high as 250 after 22,0'hours;after 244 hours, and had only declined t0-'185 in the interim between484 and 508 hours;

by the followweight polymers useful as lubricating oils.

considerable amount of alpha olefins.

ence of alpha olefins is considered to be very The amount of waterproduced during this tie riod as cc. per cubic meter of hydrogen andcarbon monoxide consumed also varied widely ranging, irom about 12 toabout -and averaging be e t eB- u ine a l th m of eration, the test dataon the hydrocarbons prodnced in the process showed the presence of a Thepresbeneficial'in that the alpha olefins are valuable feed stocks forpolymerization to high molecular The ratio of -;a.;lpha, to beta olefinsproduced during the first: 5118 hours of operation ranged from about4.6-to as high as 4.7 and the sample obtained just previous to the endof the first 508 I hour) period showed an alpha olefin to beta oleflnratio of 4.3.

Up to-998 hours operation the carbon monoxide conversion in mole percent slowly declined from 91 to 82.5;while the selectivity ratio ofCrhydrocarbons. ,to. total product in mole per cent .re;-. mained fairlyconstant, the dataqshowinga 744655- seiectivity after 998 hoursoperation with. the improved cat'alystr'of the present invention; yieldof Ca hyd'rocarbonssin cc. per cubic meter of hydrogen and carbonmonoxide consumed after 508 hours was 185 and after 998 hours'was stillly-some fluctuation of yields during this period was: observed with asmuch as 228 cc.. oiCI.+ hydrocarbonsbeing produced per cubic metero!hydrogen and'carbon monoxide consumed with the: greater amount of thedata showing the production to 'vary between 1'10 and 190' cc.- The.

time was in the range from about 24 to' 4'2'caper cubic meter-consumption of hydrogen andcarbonmonoxide. The ratio of alpha tobetaolefins-declined slightly duringthe period to'below The improvedcatalyst of the present invention was" continued in use with a slightdecline in activity and; selectivity until after '1088h0ursthe catalyst"was reduced with hydrogen at 700 F: for -24hours'at 1000- v./v./hr. andat atmospheric pressure. After this treatment, the catalyst was again'used in the synthesis of. hydrocarbons from hydrogen. andcarbonmonoxi'de. for a total or 17.36"

, After the treatment subsequent to. 10818 hours. employment; as.catalyst the. mole. percent carbon monoxide conversion was raisedto 99.4while the-selectivity ratio of. Cit hydrocarbons. to total.

productwas .7,0=7.%. The yield of 0 hydrocarbons. after. the foregoingtreatment showed only L49. cc.v pervcubic meter or hydrogeniand. canfora, totala of- 1520; hours,v it;was. then. given assim. ilar reductiontreatment: as that employed .aften 1088' hours: This-second: treatment,however; was-1 not as beneficia-i as the nrst; and it'was necessarytoterminatatherun afteu1'l36 hours.

Asmentioned before; the temperature em played in the 'outsct was 575"F., a pressure off pounds and a feed rateof' 20o v. /v./hr. Thistemperature: was raised after 628-"hours-oi operalien te-585 *FL' andin-the period bet'weerr'iw hours iintil the-end t the run was'maintainedat 500a .t. -w i i i While the foregoing run was terminateda'fterl It will be apparent fromthe fo'regoing data that alcohol towhich wasfadded a weighed emanate ferro-ferric oxide whichwasfthoroughlymixed the improved catalyst of the present invention maybeused for periodsup to 1000 hourskand higher. while. yet obtaining I.substantial conver-a sion, selectively, and yield (of C4 and: higherhy-i drocarbons While notmentioned in the foregoa ing description of therun, the amount of oxy-;

genated material in the hydrocarbonsproduced:

was maintained at a low. figure throughoutthe 11111 11. l 1 it Incontrast to the above run, an unpromoted ferro-ferric oxide: catalystoxidized innthe presence. 50! air and: subsequently reduced underwatamospheric conditions described above wasiemployed under. similar runconditions. The selectivitiesvxand yields of useful products were considerably lower for the unpromoted catalyst than; were obtained in the;case of the promoted catalyst. For .example the *unpromoted catalystpermittedthe production 1 of. only 1 100 cc of @6 4 and heavierproducts; per cubic meter of 1 hydro gen and carbon monoxide consumed.Further-t more. the"unpromotedocatalyst possessed aivery;

short ilife and after only-100 hours ofoperation...

the yields: of useful products were reduced; to. 60. cc. of Cd per.cubic meter of hydrogen. and car;

bon monoxide consumed requiring termination yof the;run.w.;'r: 1; i .1In another example, 340 parts of "F(NO3)3.9H2O

was dissolved in distilled H2O. A dilute solution of NH4OH was added tothe solution to precipitate Fe(OH)3. This was filtered and to thefiltrate a solution of 50 parts of solid KOH dissolved in distilledwater was added. The mixture was stirred to a smooth paste whilecontrolling the temperature. To the cooled material 50 parts of brominewas added below the surface of. the solution while stirring vigorously.Solid KOH was then added in small quantities until saturation wasobtained with the KOH being added to excess. During the addition of theKOH the temperature was maintained no higher than 41 C. and atapproximately 25 C. The solution was then carefully heated to 60 C. forone half hour, heat removed and. the solution cooled. Afterapproximately 24 hours, the upper half of the material, hereafterreferred to as the upper layer,

was removed. The upper layer and the bottom half, referred to as thelower layer, was then evaporated under vacuum at a temperature of 47 C.for two weeks. After this period both the upper layer and lower layerwere removed from the heat treating operation and washed free of KOH byrepeated separate washings with 95% ethyl alcohol. The washed sampleswere filtered and dried under a vacuum. The upper layer was analyzed asfollows:

Per cent F6203 62.5 K2Fe04 37.5

A weighed amount of material having the above composition was thensuspended in 95% ethyl by stirriiigto form a 's'mootli slurry. Theslurry was dried in anoven 'at 959 C. with air circulat ing freelywfor aperiod-"of 48 hours. The temperature was their raised to about11110 C.and main- 1 tained, withwthe exception ofua 12 hour-period when thetemperature: rose to about C., for

threeweeks. The dried material waspilledinto inch'pi11swhich" wereheated, for 4 /2 hours;

in the. presence: of .an oxygen-containing atmosphere at 1000 F.following which the material:

was allowed tolcoolrin air to atmospheric temperature." The''catalystprepared in the foregoing manner comprised 2.%:. by weightKzFe04 and 98%- iron oxide and was then employed for the syn-.

thesis ofthydrocarbon's from carbon monoxide andihydrogen'. after beingreduced in thepresence ofthydrogen for 24hours at a temperature of; '700E.v;and at atmospheric pressure. During the reduction treatment thehydrogen was passed over. the catalyst at the Irate of .1000. volumesIof.

hydro finwperl volume of catalyst per hour. A

synthesis 1 gas L mixture t comprising one. part 1. 1

hydrogen erg parttofacarbon. monoxide was r em-:. ployedastthe; feedstock, the. conditions of opera-y: tion being l5.0pound spressure, atemperatureot ee o es oi 1 e 5 id atf edtr W Y? maoicet perhourm man rms r aihe catal s i was fo d at r.

fecti yields of C and heavier hydrocarbons e obtainednwith the improvedmethod r c b c is greatly superior to a catalyst which has not beenpromoted with potassium ferrate.

While examples of temperature and pressure conditions suitable for usein the practice of the present invention have been given to illustrateits advantages, it will be obvious to workers skilled in the art thattemperatures and pressures over a substantial range may be employed andgood results obtained. It will also be obvious that the promotingmaterial admixed with the iron or iron oxide catalyst may be presentover a substantial range and satisfactory results obtained. It is notintended that the above-cited examples limit the scope of my invention.

The practice of the invention has been illustrated by the employment ofpotassium ferrate as the alkali metal ferrate in preparing the cata- Itis within the scope of the invention to use other alkali metals thanpotassium in preparing the catalyst adapted for use in theFischer-Tropsch synthesis. For example, sochain and lithium ferrate maybe used in lieu of the potassium ferrate. Potassium ferrate, sodiumferrate, and lithium ferrate may be used, preferably in the order given,inpreparing the catalyst. The lithium ferrate will be less desirable toemploy than the sodium and potassium ferrate but under somecircumstances it may be desirable to use it.

Divisional applications based on this application have been filedcovering respectively the specie of alpha iron oxide, gamma iron oxideand ynthe Zing hydrocarbons in the foregoing;

. (ante. duced in accordance with my process forroaferric kMidQ-L'lfheonoheetions maxi idontifieclnasrtollows: ILJS. her. No; 85.3%?1;filed. June 28, 19.18., em. muse .Eatalyst'rreparationwmethod and. di-'.reotedtouthe specie of alpha :iron oxide; .U. S. SQ1'..;:INQ;.134L843,1'ifiledvfflune 213, .1918, entitled tProoaration 0t improved.earthlyst?andedireoted to-thej'ispe'cie of, gamma Monoxide; andxfier.41.113,-fi1e.d .July 129,. lfilarientitled Method; for preparingcatalyst for hydrozenationof oarborr monoxide? and directed to .cthespecie. of term ferrie-wox-ide; .i 1

-Haying Tully described. and illustrated r the. praoticeof :the presentinvention, what! wishto. claimas. new and useful and to. secure byLetters Patentis: r

- 1. A method for preparing a catalyst adapted for ruse-in a'Fischer-Tropsch synthesis which consistsnf the steps of preparing. anadmixture of -aniron oxide andal-kali metal ferrete in an amount in therange between 0.2 and 20% by weigh-mot saidiron oxide, heating saidadmixture at a superatmos'pheric temperature of about 1 80MB;- for=about-4-=hours inthe presence of an oxidizing atmosphere, and-subsequentlycontacting the admixture with a reducing atmosphere atasuperatmosph'eric temperature in the range between 700 and '1600 F'.for about 24 hours.

2. A method Qf-producing a catalyst suitablefor usein the'Fischer-Tropsch synthesis which consists'of the steps of forming analkali metal ferrate "substantiallyfree fromcontaminatingmaterial'si"admixing the alkali metal ferrate with an iron oxide inanamount sumcien-t to form;

temperature o ffabout 1060-F,. for about; 4 hours," an 'crsubsequently'redueing theheatedmass inxa. w

reducing atmosphere at a superatmospherictemperature of about'lOOfl F?for aboutz hours.

8 3. .Aimeihodin accoroaneewith claim 13in; which the alkali metalferrate is potassium forrete. plz

4. A method in accordance with claim" 21in which the-alkali metaltel-rate. is sedition-errat c. A method in accordance withclaim .2. inwhich the alkalimetal ferrate eis .lithimniermte... 6.,Acompositionadapted for use as a. catallst in the production of hydrocarbons and oxyen: atedhrdrocarbons. which consists o! a mixture: of iron oxide in anamount in the range between 553%. and some by weight and snalkaliymetalierrate in an amount in thoranze between 0.12: and 20% by weight whichmixture'has been C9D? taotedwith an oxidizing atmosphere at atoms;Denture of about 1000 F. for. about. 4. hours and then with areducingatmosphere at atoms; ture in the range between 700 and 160i! F.ion about 24 hours. I u '7'. A composition in accordance with olnimufiin which the alkali metal ferrate is potassium: ferreteo 8. A-composition in accordance :with. claim. 61. in which the alkali.. metalierrate is. lithium ferrate. i 9. A composition. inaccordancewithcloimafi in which the alkali metal ferrate 'isscnzliurn ferrate.'10. A composition adapted for use as a catalyst" in the production of.hydrocarbons and oxygen ated. hydrocarbons which consists of a mixtureof approximately 95%- by weight of iron oxide and approximately 5% byweight of potassium ferrate' whichmzixture has been heatedin thepresence of air at a temperature ofthe order of 1000 F. for about 4hours and then heated in the presence or hydrogen at a temperature'ofabout 700 F; for about 24 hours. i

MAX A. MOSESMANb I No reierences cited.

